In the continuation of this project we propose to: carry out additional family studies in the Amish population where we have found a high frequency of sacroiliitis and spondylitic disease which is less strongly associated with HLA-B27. Further delineate the HLA-D related products in the Chippewa Indians where rheumatoid arthritis occurs in a minimum of 5 percent of the tribe. Continue in vitro studies of the relationships between infectious agents and the B27-associated diseases, now using more serologically specific organisms and lymphocytes from subjects known to have exposure to these agents. Continue to explore several genetically-related phenomena (T cell function, complement component deficiency and auto-antibodies) and their relation to HLA-D in families with systemic lupus erythematosus, Sjorgrens syndrome and polymyositis.